Chap. Till.] SEXUAL SELECTION. . 289 



surviving to this age, and which immediately gave an ad- 

 vantage to certain males, by rendering them more attrac- 

 tive to the females, would be likely to be preserved. No 

 doubt some of the variations in brightness which occurred 

 at an earlier age would by chance be preserved, and 

 eventually give to the male the same advantage as those 

 which appeared later; and this will account for the young 

 males commonly partaking to a certain extent (as may be 

 observed with many birds) of the bright colors of their 

 adult male parents. If only a few of the successive varia- 

 tions in brightness were to occur at a late age, the adult 

 male would be only a little brighter than the young male ; 

 and such cases are common. 



In this illustration I have assumed that the young 

 varied in a maimer which was of no service to them ; but 

 many characters proper to the adult male would be actu- 

 ally injurious to the young — as bright colors from making 

 them conspicuous, or horns of large size from expending 

 much vital force. Such variations in the young would 

 promptly be eliminated through natural selection. With 

 the adult and experienced males, on the other hand, the 

 advantage thus derived in their rivalry with other males 

 would often more than counterbalance exposure to some 

 degree of danger. Thus we can understand how it is that 

 variations which must originally*have appeared rather late 

 in life have alone or in chief part been preserved for the 

 development of secondary sexual characters ; and the re- 

 markable coincidence between the periods of variability 

 and of sexual selection is intelligible. 



As variations which give to the male an advantage in 

 fighting with other males, or in finding, securing, or charm- 

 ing the female, would be of no use to the female, they will 

 not have been preserved in this sex either during youth or 

 maturity. Consequently such variations would be ex- 

 tremely liable to be lost ; and the female, as far as these 



